The present invention relates to a charge and deflection control type ink jet printer and, more particularly, to such a type of ink jet printer in which an ink jet head section, a charging section and a deflecting section are configured in a single module, or unit, which may be replaced by a user, thereby enhancing the ease of maintenance.
An ink jet printer of the type described usually includes an ink jet head, a charging electrode, deflecting electrodes, a gutter, pumps, an ink reservoir, and others. As well known in the art, an ink drop to print out information is charged by the charging electrode in response to a charge signal and, then, deflected by the deflecting electrodes on the basis of the amount of charge so as to impinge on a paper. On the other hand, an ink drop not to print out information is caused to fly straightforward without being deflected, then caught by the gutter, then collected in the ink reservoir by the pump, and then returned to the ink jet head to be used again.
In the prior art ink jet printer having the above construction, the ink jet head, the deflection electrodes, the gutter and others are arranged at remote positions from each other on a carriage. This bring about a problem that every time defective print-out occurs due to stopping of a nozzle of the ink jet head, deposition of dust particles on the charging and deflecting electrodes, and/or solidification of ink, which are mostly frequently encountered with an ink jet printer of the type described, a serviceman has to be sent for to take an appropriate measure such as repair or replacement. Especially, in the event of replacement of the head whose nozzle is stopped up, a serviceman needs to adjust and set up the direction of ejection with respect to the height and width of the gutter and the drive voltage, which differ from one head to another.
Japanese Patent Publication No. 55-47595 discloses a charge and deflection control type ink jet printer in which pumps, an ink jet head, deflection electrodes and other parts are interconnected by tubes and leads. A drawback with this kind of ink jet printer is that when the printer becomes inoperable due to clogging of the head, contamination of the electrodes, and other causes, it is impossible for the user to replace the parts or to perform maintenance without the help of a serviceman.